//Given a singly linked list, determine if it is a palindrome. 
//
// Example 1: 
//
// 
//Input: 1->2
//Output: false 
//
// Example 2: 
//
// 
//Input: 1->2->2->1
//Output: true 
//
// Follow up: 
//Could you do it in O(n) time and O(1) space? 
// Related Topics 链表 双指针
//双指针逆序的后半链，再判断是否回文

//leetcode submit region begin(Prohibit modification and deletion)
/**
 * Example:
 * var li = ListNode(5)
 * var v = li.`val`
 * Definition for singly-linked list.
 * class ListNode(var `val`: Int) {
 *     var next: ListNode? = null
 * }
 */
class Solution {
    fun isPalindrome(head: ListNode?): Boolean {

    }
}
//leetcode submit region end(Prohibit modification and deletion)
